架构ViewModel中的BaseObservable字段未添加任何观察者回调

public class MyViewModel extends BaseObservable {
    private String data;

    @Bindable
    public String getData() {
        return data;
    }

    public void setData(String data) {
        this.data = data;
        notifyPropertyChanged(BR.data);
    }
}

public class MyActivity extends AppCompatActivity {
    private MyViewModel viewModel;
    private ActivityMainBinding binding;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        binding = DataBindingUtil.setContentView(this, R.layout.activity_main);
        viewModel = new MyViewModel();
        binding.setViewModel(viewModel);
        // 监听BaseObservable字段的变化
        viewModel.addOnPropertyChangedCallback(new Observable.OnPropertyChangedCallback() {
            @Override
            public void onPropertyChanged(Observable sender, int propertyId) {
                if (propertyId == BR.data) {
                    // BaseObservable字段变化时的处理逻辑
                }
            }
        });
    }
}